Always push start your car.
Contact surfaces of relay contactors and starters are often made of materials such as silver, silver alloy, or silver cadmium oxide. These materials provide good electrical conductivity, resistance to arcing and welding, and durability for repeated operations.
head lights stuck on and turning on and off does not change it.
Most starters are grounded through their mounting bolts and contact with the engine. Some starters have a braided ground cable between the starter and engine or frame. The arcing occurred because you shorted between an electrically "hot" connection and ground , i.e. the manifold.
Some voltage must be present but the current causes the arcing.
your local librarie should have a mechanics manuual that you can photo copy ! Good Luck !
A shorted coil or shorted coils in the rotor will cause arcing at the commutator. It should also be noted that if the brushes are damaged badly enough where they make contact with the commutator, this can cause arcing. Oh, and let's not forget that a stuck brush or brush spring will prevent a brush from making proper contact with the commutator. Arcing can result from that, too.
Arcing is electrical current jumping across a gap, or creating an arc, as in a spark plug firing, or lightning arcing across the sky.
the temperature control actuator is on top of the heater box under the dash. you have to remove the dash to get at it. a repair manuual will show what screws to remove
The adjustments are pretty obvious on the the top of the transmission under the air intake and exhaust plumbing.
A shorted coil or shorted coils in the rotor will cause arcing at the commutator. It should also be noted that if the brushes are damaged badly enough where they make contact with the commutator, this can cause arcing. Oh, and let's not forget that a stuck brush or brush spring will prevent a brush from making proper contact with the commutator. Arcing can result from that, too.
high voltage breaking capacity
You have a wire that is loose and arcing.